Metal-Ion Induced Surface Modification for Durable Hydrophobic Wood

Stable and durable hydrophobic wood surfaces hold great potential in the wood industry. However, wood tends to absorb water due to the abundant surface hydroxyl groups. A facile and effective approach is proposed here to construct hydrophobic and damage-tolerant wood surface by coordinating the hydroxyl groups with metal ions. By immersing the pristine wood blocks into salt solutions and followed by drying, the modified wood surface exhibits a hydrophobic behavior. In particular, the surface of Zr(4+)ion modified wood (Zr-Wood) demonstrates the most dramatic modification effects. The surface vertical to wood growth direction has a water contact angle of 145 degrees, while the surface along the wood growth shows a water contact angle of 139 degrees. Moreover, the wear resistance and durability are explored and the results prove that Zr-Wood possesses good tolerances against sandpaper abrasions and corrosive solutions. The hydrophilic to hydrophobic transition is ascribed to the formation of metal complexes between ions and hydroxyl groups. Such method is promising for wood preservation and can extend the use of wood.